Feature Article
Load Stability Article contributed by STUART EDWARDS, HEAVY LIFT ENGINEER
In the crane industry, lifting loads safely is a key component to the success of any project. When selecting rigging for a lift, the capacity of the lifting points and rigging often are the first items to be addressed, closely followed by strength of the load to support itself and various site constraints such as allowable head room and crane limitations. Whilst these areas are very important, the overall stability of the load is crucial in successfully completing a lift. If this stage of lift planning is ignored, it may result in damaged loads, injury or even fatality. This article focuses on how to identify when a load may be unstable.
such as wind, acceleration of the crane etc. as the COG wants to go back down and restore the load back to equilibrium, much like hanging a broom from the handle at the top. Figure 1 below show a stable rigging arrangement.
Generally, any loads with a rigging arrangement that lifts from the top via the use of lift points that are above the centre of gravity (COG) will be stable. This is because the centre of gravity of the load is below the lift points and if there is an external force
Lift points above the COG >> LOAD IS STABLE This type of load will not tip over once it is freely suspended.
Figure 1 - Stable lift with lift points above the centre of gravity
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LIFTING MATTERS
ISSUE Q4 2020
